Why not? PHP was designed from the ground up for website programming, and nothing else. Sure it has evolved a little and you can mis-use any tool, but PHP's principle purpose is still to spit out HTTP; The H in PHPP === the H in HTTP.
I've tried a few others, but I must say that I keep coming back to PHP. I like to keep things servers-ide and am one of those paranoiacs who surf with JS, so others may do so too. If I use only PHP the miss nothing.
You can handcraft your site, or you can use templating like Smarty, etc, or you can use a full blown CMS (see http://www.cmsmatrix.org/).
But unless you are looking to learn new skills, since you already know PHP why woudl you want to use anything else?